Negative pattern and hollow mold for casting compound reflector members



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B. J. PIQUE NEGATIVE PATTERN AND HOLLOW MOLD FOR CASTING COMPOUNDREFLECTOR MEMBERS Original Filed March 19. 1951 July 8, 1958 I N VEyNgHQFIG?) United States Patent NEGATIVE PATTERN AND HOLLOW MOLD FOR CASTINGCOMPOUND REFLECTOR MEMBERS Baudilio Jesus Piqu, Marianao Township, CubaOriginal application March 19, 1951, Serial No. 216,367, now Patent No.2,719,327, dated October 4, 1955. Divided and this application August19, 1954, Serial No. 450,982

2 Claims. (CI. 18-34) My invention relates to improvements in negativepattern and hollow mold for casting compound reflector members. Thisinvention comprises subject matter disclosed in my copending applicationSerial No. 216,367, filed March 19, 1951, for Centrifugal CastingProcesses and Apparatus for Casting True Paraboloidal Convex SurfacePatterns, now Patent No. 2,719,327, issued on October 4, 1955, of whichthis is a divisional application. It has been designed more particularlyas a device for making commercially practicable the adaptation of thecomplementary parts combined in my invention described and claimed inthe United States Letters Patent No. 2,501,140, issued March 21, 1950,for Electric-Light Projecting Reflector.

The present invention provides a hollow mold comprising a negativepattern with true half paraboloidal convex surfaces for casting compoundreflector members.

One of the advantages of these negative patterns is that they are madewith accurately formed paraboloidal convex surfaces.

Another advantage of these negative patterns and hollow mold are theiradaptation to manufacture compound reflector members made directly bysimple casting.

The construction of these negative patterns comprises a centrifugalcasting process in apparatus for casting true paraboloidal convexsurface patterns.

It is known that the best concave surface produced with extreme accuracyis the paraboloid of revolution, because when a liquid body is containedin a receptacle which rotates uniformly, the surface of the liquid takesthe form of an accurate paraboloid. The natural surfaces of liquids inan absolute or relative state of repose are extremely accurate. Whenthis liquid consists of a solid in fused condition, and is cooled whilecontinuing at the same angular velocity, the liquid body will solidifyconserving the paraboloidal surface.

When two bodies having different physical conditions referring to theirspecific weights and fusion points, are contained in fused conditionwithin a receptacle, the heavier liquid will be under the lighterliquid. When these liquids are in absolute or relative state of repose,the liquid joint surface will have equal shape than the top liquidsurface. When these two liquids are contained in a receptacle whichrotates uniformly, the top liquid surface and the liquid joint surfacetake equal forms of accurate paraboloid. If the receptacle continues atthe same angular velocity while the liquids are cooling, these liquidbodies will solidify comprising paraboloidal surfaces accurately formed.

The provision of an apparatus for centrifugal casting comprising areceptacle that rotates uniformly having means for holding determinatequantities of two melted materials according to the angular velocityapplied to said receptacle, and means for making a pair of half patternshaving an inner plane border limiting half convex paraboloids and abevel border of uniform thickness at their outer peripheries. The meltedmaterials having different physical conditions with each other,referring to their spe- 2,841,825 Patented July 8, 1958 cific weightsand fusion points, will form separable composite casting with trueparaboloidal surfaces. The apparatus may be so operated in a centrifugalcasting process that each pair cast in the apparatus will have adifferent convex curvature from every other pair cast in the sameapparatus and having the same thickness of bevel border at their outerperipheries.

As wrought concave and convex surfaces are not as accurate as it isdesired for patterns, one of the objects of my improvement is to formnegative patterns having true half paraboloidal convex surfaces.

Another object is to provide a negative pattern constituted with twodifferent half patterns having each one halves an inner plane borderlimiting half convex paraboloid and a bevel border at their outerperiphery. Said both dilferent half patterns being joined with eachother through their inner plane border and thus being fitted andattached throughout their peripherical bevel border on a bevel ringsupport, to be used as compound surface pattern in pressing apparatus orin hollow mold.

A further object of my invention is the provision of a hollow moldadapted to manufacture compound reflector members by a simple casting.

Referring to the drawings: Fig. 1 presents a vertical sectional view ofa centrifugal casting apparatus for making a pair of half paraboloidalpatterns; Fig. 2 is a sectional view of a hollow mold showing the objectof this invention; and Fig. 3 is a sectional view through the line 3-3of Fig. 1. Similar numerals refer to the same or similar parts throughthe figures.

An apparatus for centrifugal casting comprising a receptacle A having acurved base 1 with the inner side forming a rippled paraboloidal surface2. Said receptacle A is provided with a cylindrical end 4 having aconical edge at the periphery thereof.

A thin blade 9 having a paraboloidal border is fitted and attachedby itsborder on the inner paraboloidal rippled surface 2 of said receptacle A.

A rotor axle 3 attachedto the receptacle A, is placed vertically in amachine not shown in the drawings, which rotates uniformly together withthe receptacle A around its symmetrical axis.

A melted material 10 is put within the receptacle A to be adapted as anadjustable mold according to the angular velocity applied in theapparatus to said receptacle A.

A conical ring 5 having an inner sharp edge 6, is assembled with saidcylindrical end 4 at the periphery of receptacle A, being fitted bymeans of a ring flange 7.

Another melted material 11, having lighter specific weight and higherfusion point than the first one, is put Within the receptacle A forcasting a pairof half patterns 1111 upon said first melted material 10.

The cylindrical end 4 with its conical edge is adapted at the peripheryof receptacle A to regulate the amount of melted material 10. Theconical ring 5 with its inner sharp edge 6 is adapted upon thecylindrical end 4 of receptacle A to regulate the amount of meltedmaterial 11 and to perform a bevel border 14 at the outer peripheries ofthe casting patterns. 1

An annular pan 8 is located separately surrounding the rotor receptacleA.

When the receptacle A, without the conical ring 5, rotates withpredeterminate velocity having within it the melted material 10, thismaterial 10 will flow upward -by receptacle A, to be shaped according tothe concave curva- 3 ture required to constitute an adjustableparaboloidal mold.

After this, fitting the conical ring 5 upon the cylindrical end 4 ofreceptacle A, and then, when said receptacle A rotates with the samepredeterminate velocity, the other melted material 11 having lighterspecific weight and higher fusion point than the first material 10, isput within the receptacle A and upon the melted material 10, whence, thesecond melted material 11 flows upward by centrifugal force and theexcess of this material 11 will be spilled out from inner sharp edge 6of conical ring 5 to the annular pan 8, and an appropriate quantity ofsaid material 11 is retained by said conical ring 5, according to theangular velocity with which said receptacle A is rotated, to be shapedhavingtheir contours defined. The liquid joint surface 12 will be apredeterminate true paraboloidal surface as same as the top liquidsurface 12.

When the materials and 11 are cooled by lowering their temperaturebetween the temperatures of fusion points of both materials 10 and 11,the material 11 having higher fusion point than the material 10, will besolidified, and the material 10 will continue melted, forming separablecomposite casting. In this condition, after take out the conical ring 5,the solidified material 11 may be taken out by a suction cup.

The thin blade 9 is adapted in the receptacle A to disjoint halves ofsaid casting pattern 11 through a plane holding the axis of paraboloidalsurface 12, and for performing an inner plane border 9 limiting halfconvex paraboloids 12-12 and thus obtaining a pair of half patterns11-11.

Furthermore, making another pair of half patterns 11'11', by distinctangular velocity of receptacle A than that of the first patterns 11-11,after having been corrected the quantity of melted material 10 accordingto the angular velocity applied to the receptacle A in accordance withthe curvature'required in such pair of half patterns 11'-11'.

Each different pair of half patterns 11-11 and 11'-11 will have a bevelborder 14 with the same uniform thickness at their outer periphery, itshaped by the conical ring 5, and an inner plane border 9' limiting halfparaboloids throughout a plane comprising the axis of said halfparaboloids, it shaped by the thin blade 9.

Now, two different half patterns 11 and 11', taken from two differentpairs of half patterns, will be joined through their inner plane border9' and welded together to constitute a compound negative pattern havingtwo half convex paraboloids 12 and 13 with different convex curvatureand displaced from each other along their paraboloidal axis, and ameniscus plane, as it is shown in Fig. 1 between the paraboloidalsections 12 and 13, will be conformed between the inner periphery ofboth displaced half convex paraboloids 12 and 13 and comprising theirparaboloidal axis according to the inner plane border 9' of said halfpatterns 11 and 11. These half patterns 11 and 11 will have theirperipherical bevel border 14 coinciding in conical ring section.

This negative pattern 11-11, which comprises true half paraboloidalconvex surfaces 12-13, will be used as compound surface pattern inpressing apparatus or in hollow mold as is shown in Fig. 2.

A plate base having a conventional ring support 15 with a bevel ringsurface. The compound negative pattern 11-11, as described, is adjustedon the bevel ring surface of ring support 15, throughout itsperipherical bevel border 14.

A cover member 16 having an inner paraboloidal concave surface 17 and abevel border at-its periphery. The

cover member 16 is adapted, throughout its peripherical bevel border 14,on the ring support 15, inwalling thenegative pattern 11-11 and thebevel ring surface of ring support 15 in a hollow mold 19.

7 4 member 16 will be inwalling the negative pattern 11-11 and near toface with their displaced half convex paraboloids 12-13.

The bevel ring surface of ring support 15 will form the end of saidhollow mold 19, adapted between the outer periphery of the innerparaboloidal concave surface 17 of cover member 16 and the outerperiphery of the two half convex paraboloids 12 and 13 of negativepattern 11-11.

Thecover member 16 has a hole 18 communicating the hollow mold 19 withthe exterior.

This hollow mold 19 comprises: a conventional ring support 15 having abevel ring surface, a negative pattern 11-11 comprising two half convexparaboloids 12 and 13 having different curvature displaced from eachother along their paraboloidal axis, said negative pattern 11-11 isadjusted on the bevel ring surface of ring support 15 coinciding theirhalf convex paraboloids 12-13 with the bevel ring surface. of ringsupport 15 throughout their outer periphery, a meniscus planercon-vformed between the inner periphery of said displaced half convexparaboloids 12-13 and comprising their paraboloidal axis, and a covermember 16 having an inner paraboloidal concave surface 17 inwalling saidnegative pattern 11-11 and substantially near to face with saiddisplaced half convex paraboloids 12-13, the cover member 16 is adjustedon the ring support 15 inwalling the bevel ring surface of said ringsupport 15. The

' casting is made through the hole 18 into the hollow mold Theinnerparaboloidal concavesurface 17 of the cover 19 for making compoundreflector members.

What I claim is:

1. The combination, in a hollow mold comprising a ring support and acover member, of a negative pattern, comprising two half convexparaboloids having different curvature displaced from each other alongtheir paraboloidal axis, and a meniscus plane conformed between theinner periphery of said displaced half convex paraboloids and comprisingtheir paraboloidal axis, with an inner paraboloidal concave surface insaid cover mem-, ber inwalling said negative pattern near to face withsaid:

displaced half convex paraboloids, and a bevel ring surface in said ringsupport located between the outer periphery of said half convexparaboloids and said inner paraboloidal concave surface, and thus saidhollow mold being adapted for casting compound reflector members.

2. In a hollow mold comprising a conventional ring support having abevel ring surface, the combination of a negative pattern comprising twohalf convex paraboloids having different curvature displaced from eachother along their paraboloidal axis, and a, meniscus plane conformedbetween the inner periphery of said displaced half convex paraboloidsand comprising their paraboloidal axis, with a cover member having aninner paraboloidal concave surface inwalling said negative pattern andnear to face with said displaced half convex paraboloids, said negativepattern having their half convex paraboloids coinciding with the bevelring surface of said ring support throughout their outer periphery, saidcover member adapted on the ring support with its inner paraboloidalconcave surface inwalling the bevel ring surface of said ring support,and thus said hollow mold being adapted for casting compound reflectormembers.

References Cited in the file of this patent UNITED STATES PATENTS

